1. Field of the Invention
This invention relates to a core material for laminates and a method for manufacturing the same, more specifically, it relates to a core material for giving a laminate which is light in weight and excellent in strength by being laminated with an FRP or the like such as an unsaturated polyester, and a method for manufacturing the same.
The core material for laminates of this invention is useful for ships, boats, pools, and various tanks such as reservoirs, bath tubs and the like.
2. Description of the Prior Art
Hitherto, as for the core material of this kind, there has been used, as shown in FIG. 9 and FIG. 10, a core material 1 of crosslinked polyvinyl chloride resin foam board 2 provided with slits 4 in longitudinal and horizontal directions with a non-slit portion 3 of an appropriate length left from one side of the board 2 and laminated with porous sheet 9 on the side of the non-slit portion 3. There may be cases for the porous sheet 9 to be omitted.
In forming, for example, a hull structure having curved portions as shown in FIG. 11 by laminating such a core material 1 with an outer FRP 6 through a putty 5 and further laminating with an inside FRP 7, the core material 1 is provided in stretched state on the putty 5 along the curved configration of the hull with rupture of the non-slit portion 3, and the putty 5 enters and is filled in the slit 4 and the ruptured portion 8 of the non-slit portion 3.
However, as the space in the ruptured portion 8 is small and its upper end is substantially closed, it is not possible to discharge air perfectly, and accordingly the putty 5 is cured under the state of sealing in air, and further the inside FRP 7 is coated on the core material 1.
As the structure like the above one contains air inside and as the putty 5 is not fully filled in spaces formed by the small pieces of the foam board 2, water which entered from the outside FRP 6 during use is pooled not only to increase the ship weight, but also to provide inconveniences including an increase in energy consumption. Further, because the putty 5 does not fully intrude into spaces formed between the small pieces of the foam board 2, the reinforcing rib effect for increasing strength is not sufficiently provided.